Relationship Between the QT Indices and the Microvolt-Level T Wave Alternans in Cardiomyopathy

概要

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The relationship between the QT indices and microvolt-level T wave alternans(TWA)is unknown in cardiomyopathy, so the present study examined 86 patients with cardiomyopathy who experienced TWA during exercise testing(EXT). The QT interval(QT), duration from the Q wave to the peak of the T wave(QTp), duration from the peak to the end of the T wave and the dispersion of these parameters were measured by 12-lead electrocardiogram at rest and during EXT. In dilated cardiomyopathy(DCM), TWA was positive(TWA+)in 19 patients and negative(TWA-)in 17. No significant difference was observed between the TWA+ and TWA- groups in any parameter. In hypertrophic cardiomyopathy(HCM), TWA was positive in 24 patients and negative in 12. Max QTc, max QTpc and mean QTpc during EXT in the TWA+ group were significantly longer than those in the TWA- group. The sensitivity of TWA for ventricular tachycardia(VT)was high in DCM and HCM, and that of max QTc>500 ms during EXT for VT was high in HCM(93%). TWA is a useful predictor for VT in DCM and HCM, and prolonged max QTc during exercise has a prognostic value in HCM. Repolarization abnormality during exercise plays an important role in the genesis of VT in cardiomyopathy.
社団法人日本循環器学会の論文
2001-10-20